Systems and methods for producing a single crystal silicon ingot using a vaporized dopant

Abstract

An ingot puller for producing a doped single crystal silicon ingot includes a housing defining a chamber, a crucible disposed within the chamber, and a dopant injector attached to and extending into the housing. The chamber is maintained at a first pressure. The dopant injector includes a reservoir for containing a liquid dopant, a feed tube positioned within the chamber and connected to the reservoir, and a vaporization cup positioned within the feed tube and the chamber.

What is claimed is: 
     
         1 . An ingot puller apparatus for producing a doped single crystal silicon ingot, the ingot puller apparatus comprising:
 a housing defining a chamber maintained at a first pressure;   a crucible disposed within the chamber; and   a dopant injector attached to the housing and extending into the chamber, the dopant injector comprising:
 a reservoir for containing a liquid dopant, the reservoir maintained at a second pressure greater than the first pressure; 
 a feed tube positioned within the chamber and connected to the reservoir; 
 a vaporization cup positioned within the feed tube and the chamber, wherein the vaporization cup receives the liquid dopant from the reservoir and vaporizes the liquid dopant into a vaporized dopant at the first pressure; and 
 an actuatable valve operable to selectively channel the liquid dopant from the reservoir to the vaporization cup when actuated to reduce a pressure of the liquid dopant from the second pressure to the first pressure. 
   
     
     
         2 . The ingot puller apparatus of  claim 1 , wherein the feed tube includes a first end positioned proximate a surface of a melt to direct the vaporized dopant to the surface. 
     
     
         3 . The ingot puller apparatus of  claim 1 , wherein the vaporization cup comprises:
 a receiver to receive the liquid dopant; and   a vaporization plug positioned within the receiver to vaporize the liquid dopant into the vaporized dopant at the first pressure.   
     
     
         4 . The ingot puller apparatus of  claim 3 , wherein the vaporization plug divides the receiver into a liquid reception portion and a vapor channel portion. 
     
     
         5 . The ingot puller apparatus of  claim 4 , wherein the receiver defines channels in the vapor channel portion that channel the vaporized dopant to the feed tube. 
     
     
         6 . The ingot puller apparatus of  claim 5 , wherein the vaporization plug includes a first end and a second end and defines vapor channels extending from the first end to the second end, and wherein the vaporized dopant is channeled through the vapor channels into the channels defined by the receiver. 
     
     
         7 . The ingot puller apparatus of  claim 1 , wherein the dopant injector includes a bellows for moving the feed tube within the chamber. 
     
     
         8 . The ingot puller apparatus of  claim 1 , further comprising a heater that radiates heat into the chamber to melt polycrystalline silicon in the crucible and heat the vaporization cup. 
     
     
         9 . The ingot puller apparatus of  claim 8 , wherein the first pressure is below atmospheric pressure, wherein the vaporization cup is maintained at the first pressure below atmospheric pressure in the chamber and heated by radiant heat from the heater such that the vaporization cup operates to vaporize the liquid dopant by flash evaporation. 
     
     
         10 . The ingot puller apparatus of  claim 1 , further comprising an actuator operably connected to the valve to selectively actuate the valve. 
     
     
         11 . The ingot puller apparatus of  claim 10 , wherein the valve is operably connected to the actuator by an actuation shaft, wherein the dopant injector further includes a reservoir tube that circumscribes the actuation shaft to define the reservoir therebetween. 
     
     
         12 . The ingot puller apparatus of  claim 1 , wherein the valve is positioned between the reservoir and the vaporization cup. 
     
     
         13 . The ingot puller apparatus of  claim 1 , wherein the actuatable valve is actuatable from an open position, in which liquid dopant is channeled into the vaporization cup, and a closed position, in which the actuatable valve closes the reservoir from the vaporization cup to maintain liquid dopant within the reservoir and to maintain the first pressure within the chamber. 
     
     
         14 . An ingot puller apparatus for producing a doped single crystal silicon ingot, the ingot puller apparatus comprising:
 a housing defining a chamber maintained at a pressure below atmospheric pressure;   a crucible disposed within the chamber;   a heater to radiate heat in the chamber; and   a dopant injector attached to and extending into the housing, the dopant injector comprising:
 a feed tube positioned within the chamber to receive a liquid dopant; 
 a vaporization cup positioned within the feed tube and the chamber to vaporize the liquid dopant into a vaporized dopant; and 
 an actuatable valve operable to selectively channel the liquid dopant to the vaporization cup when actuated to reduce a pressure of the liquid dopant; 
   wherein the vaporization cup is maintained at the pressure below atmospheric pressure in the chamber and heated by radiant heat from the heater such that the vaporization cup operates to vaporize the liquid dopant by flash evaporation.   
     
     
         15 . The ingot puller apparatus of  claim 14 , wherein the dopant injector comprises a reservoir for containing the liquid dopant, wherein the valve selectively channels the liquid dopant from the reservoir to the vaporization cup. 
     
     
         16 . The ingot puller apparatus of  claim 15 , wherein the reservoir is maintained at a pressure above the below atmospheric pressure of the housing. 
     
     
         17 . The ingot puller apparatus of  claim 14 , wherein the vaporization cup comprises:
 a receiver to receive the liquid dopant; and   a vaporization plug positioned within the receiver, wherein the vaporization plug divides the receiver into a liquid reception portion and a vapor channel portion, and wherein the vaporization plug is heated by the radiant heat and vaporizes the liquid dopant into the vaporized dopant.   
     
     
         18 . The ingot puller apparatus of  claim 17 , wherein the vaporization plug includes a first end and a second end and defines vapor channels extending from the first end to the second end, and wherein the vaporized dopant is channeled through the vapor channels into the vapor channel portion of the receiver. 
     
     
         19 . The ingot puller apparatus of  claim 14 , further comprising an actuator operably connected to the valve to selectively actuate the valve.